Strut Attachments For External Fixation Frame

ABSTRACT

Disclosed herein are strut attachments for external fixation frames. The strut attachments provide solutions for frame configurations in which it is not possible to attach a strut at its ends to corresponding rings. The strut attachments may be considered an outrigger type of mechanism that achieves more travel out of completely collapsed struts. The strut attachments, each having a pivot and a hinge joint, allow a strut to be attached on the level of a first ring and extend at least partially proximally or distally to a second ring depending on the frame of reference of the ring system. These strut attachments may be used when the fully collapsed length of the strut will not allow the rings to get any closer to one another than is needed or proscribed. In such cases, the strut attachments allow for even tighter ring to ring distance.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 17/112,398, filed Dec. 4, 2020, which is a continuation of U.S.patent application Ser. No. 15/419,596, filed on Jan. 30, 2017, whichissued as U.S. Pat. No. 10,874,433 on Dec. 29, 2020, the disclosures ofwhich are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present disclosure relates to systems and components of externalfixation frames. More particularly, the present disclosure relates tostrut attachments for varying the attachment point of a strut to ringsof such frames.

BACKGROUND OF THE INVENTION

Many different types of bone deformities can be corrected using externalfixation systems to perform the distraction osteogenesis process. Forexample, an Ilizarov device or similar external fixation system may beused. Such systems generally use rings also designated as fixationplates connected by threaded rods or struts for manipulation,lengthening, angulation, rotation, and translation of deformities ofbones. The position of a threaded rod within a hole of a ring isgenerally fixed using nuts and washers. Adjustable length or telescopicstruts are generally fixed to rings at opposite ends thereof with thelength of the struts being adjusted by changing the position of athreaded rod within a cylindrical shaft.

As the struts are manipulated, the rings or fixation plates changepositions relative to one another, causing the bones or bone segmentsattached to the fixation plates to change positions relative to oneanother, until the bone segments are in a desired position relative toone another. Fixation systems have many areas which may be improvedincluding, for example, the ease and precision with which the fixationsystem may be adjusted by a user, whether a clinician or a patient.

Telescopic struts are used to reduce/treat fractures and correctdeformities over time. Patients correct the deformities by prescribedadjustments of the struts. The lengths of the struts are adjusted overtime to change the position and orientation of the two rings withrespect to one another, which in turn repositions and reorients the bonefragments, with a goal of correcting the bone deformity. The adjustmentof the external fixator generally complies with a predeterminedcorrection plan. The struts are generally assembled in a hexapodplatform configuration consisting of six struts and gradually adjustedin length (by hand or via an instrument) to address the indicateddeformities. The disengagement of such a strut's quick releasemechanism, for example, can free the frame and allow the surgeon toquickly manipulate ring position, simplifying frame assembly andfixation to the deformity. Depending on the type of deformity, a strutmay run out of its minimum length when the telescopic lengths ofcomponents are completely collapsed. In such cases, it would preferableto have a strut connected to a respective ring about its length ratherthan at its end.

BRIEF SUMMARY OF THE INVENTION

The present invention provides solutions for frame configurations inwhich it is not possible to attach each strut at its ends tocorresponding rings. The strut attachments of the present invention maybe considered an outrigger type of mechanism that achieves more travelout of completely collapsed struts. The present invention uses a specialtype of strut, that attaches on the level of a first ring and extends atleast partially proximally or distally to a second ring depending on theframe of reference of the ring system. The strut attachments may be usedwhen the fully collapsed length of the strut will not allow the rings toget any closer to one another than is needed or proscribed. In suchcases, the strut attachments allow for even tighter ring to ringdistance.

In another embodiment, instead of having a first end of a first strutlocated proximally to a top surface of a first ring, the first end ofthe first strut is located between top and bottom surfaces of the firstring. By having a strut attachment member in the shape of a C-clamp, apivot point of the strut can consistently be at a center the ringthickness between the top and bottom surfaces thereof.

A first aspect of the present invention is with regard to the strutattachment member coupled to each strut in an external fixation system.Each strut attachment allows for two degrees of freedom between thestrut and a respective ring that the strut is coupled to. The twodegrees of freedom is obtained by utilizing one pivot joint and onehinge joint. The struts of the present invention include a threaded rodthat rotates with respect to a telescopic tube. A function of thethreaded rod being able to rotate with respect to the tube provides anadditional degree of freedom. It also allows the struts to be attachedand tightened directly to the rings. Overall, each strut will have twodegrees of freedom at each end and one degree of freedom at the threadedrod level for a total of five degrees of freedom.

A second aspect of the present invention is with regard to coupling astrut attachment member to a body of a strut. The struts have a variableattachment point that will allow it to have at least two differentattachment sites on the body of the strut. The attachment sites caneither be at the middle of the strut body or at an end of the strutbody. Coupling the strut attachment to the middle of the strut bodyprovides a tight ring to ring distance when needed.

A third aspect of the present invention is a telescopic tube havingmarkings on opposite sides of a slot about a length of the tube. Thesemarkings allow the tubes to display accurate lengths of the struts whenthe strut attachment is coupled to the strut body at its middle or atits end.

Another aspect of the present invention is an external fixation systemcomprising first and second ring members and first and second strutattachments members. The first strut attachment member is pivotablycoupled at a first end to the first ring member and at a second end to afirst end of an adjustable length strut. The second strut attachmentmember is pivotably coupled at a first end to the second ring member andat a second end to a length of the adjustable length strut.

In one embodiment of this aspect of the present invention, the firststrut attachment member includes first and second pivot portions, thefirst pivot portion pivotably coupling the first strut attachment memberto the first end of the adjustable length strut about a first axis andthe second pivot portion pivotably coupling the first strut attachmentmember to the first end of the adjustable length strut about a secondaxis perpendicular to the first axis.

In another embodiment, the first end of the first strut attachmentmember has a bore adapted to receive a fastener for securing the firstend of the first strut attachment member to at least one of a pluralityof holes in the first ring.

In yet another embodiment, the first end of the first strut attachmentmember is located proximally to a top surface of the first ring when thefirst strut attachment member is coupled to the first ring.

In still yet another embodiment, the adjustable length strut comprises arod member, a tube member and an actuation mechanism. The rod memberextends between the first end and a second end of the adjustable lengthstrut, the rod member including external threads. The tube memberextends between the first and second ends of the adjustable lengthstrut, the tube member including a hollow portion adapted to receive therod member and an engagement feature adapted to engage the externalthreads of the rod member. The actuation mechanism rotatably fixed tothe rod member, the actuation mechanism including a plurality of gearteeth extending radially outward of a longitudinal axis of the rodmember.

In still yet another embodiment, the adjustable length strut furthercomprises a protrusion member coupled to an end portion of the rodmember, the protrusion member extending substantially orthogonal to thelongitudinal axis of the rod member, the protrusion member includes acollar portion substantially surrounding the end portion of the rodmember, wherein the collar portion is freely rotatable with respect tothe end portion of the rod member.

In still yet another embodiment, the tube member includes an elongateslot extending through inner and outer surfaces of the tube member, aportion of the protrusion member extends through a portion of theelongate slot, and wherein the tube member includes visual indicia onthe outer surface thereof adjacent the slot.

Another aspect of the present invention is an external fixation systemcomprising a first ring member, a second ring member, a first strutattachment member pivotably coupled at a first end to the first ringmember and at a second end proximate to a first end of an adjustablelength strut, and a second strut attachment member pivotably coupled ata first end to the second ring member and at a second end to an outersurface of the adjustable length strut between the first end a secondend of the adjustable length strut.

Another aspect of the present invention is an external fixation systemcomprising a first ring member, a second ring member, a first strutattachment member pivotably coupled at a first end to the first ringmember and at a second end to a first end of an adjustable length strut,and a second strut attachment member pivotably coupled at a first end tothe second ring member and at a second end to one of a plurality ofpositions about the length of the adjustable length strut between thefirst end and a second end of the adjustable length strut.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the subject matter of the presentinvention and the various advantages thereof can be realized byreference to the following detailed description in which reference ismade to the accompanying drawings in which:

FIG. 1 is a perspective view of an external fixation system according toan embodiment of the disclosure.

FIG. 2A is a perspective view of a strut of the external fixation systemof FIG. 1 .

FIGS. 2B-C are perspective views of the strut of FIG. 2A with certaincomponents omitted.

FIG. 2D is a perspective view of an actuation mechanism of the strut ofFIG. 2A.

FIG. 3 is a perspective view of the external fixation system of FIG. 1with modular attachment members coupled to the struts.

FIG. 4 is a perspective view of an external fixation system according toan embodiment of the disclosure showing strut attachment members of thepresent invention coupling first and second struts to respective firstand second rings.

FIG. 5A is a perspective view of a strut with strut attachment memberscoupled to the strut in a first configuration.

FIG. 5B is a perspective view of a strut with strut attachment memberscoupled to the strut in a second configuration.

FIG. 6A is a perspective view of a strut attachment member of thepresent invention that is configured to be coupled about the body of astrut.

FIG. 6B is a partially exploded perspective view of a ring connectorportion separated from the intermediate and coupling portions of thestrut attachment member shown in FIG. 6A.

FIG. 6C is a perspective view of the ring connector portion shown inFIG. 6A.

FIG. 7 is a perspective view of a strut attachment member of the presentinvention that is configured to be coupled at an end of a strut.

DETAILED DESCRIPTION

FIG. 1 shows an external fixation frame 10 in an assembled conditionaccording to one aspect of the disclosure. Generally, fixation frame 10includes a first ring 20 and a second ring 30, with six telescopicstruts 100 a-f coupling the first ring 20 to the second ring 30. Thefirst ring 20 may also be referred to as a proximal ring or a referencering, while the second ring 30 may also be referred to as a distal ringor a moving ring. In the illustrated embodiment, each strut 100 a-fincludes a threaded portion that may thread into or out of a tubeportion, for example by interaction with quick release mechanism 130, todecrease or increase the length, respectively, of the telescopic strut.Each end of each strut 100 a-f may be coupled to the first ring 20 andsecond ring 30 via a joint mechanism, such as a ball joint, aconstrained hinge joint, or a universal joint as illustrated. The use ofuniversal joints on each end of the strut provides for six degrees offreedom of motion of the external fixation system 10. It should beunderstood that although the disclosure is generally described in thecontext of closed circular rings, the concepts described herein mayapply with equal force to other types of rings, such as open ringsand/or U-shaped rings.

In external fixation system 10, telescopic struts 100 a-f are used toreduce fractures and correct deformities over time. Patients correct thedeformities by prescribed adjustments of the struts 100 a-f. The lengthsof the struts 100 a-f are adjusted over time to change the position andorientation of the two rings 20, 30 with respect to one another, whichin turn repositions and reorients the bone fragments, with a goal ofcorrecting the bone deformity. The adjustment of the external fixator 10should strictly comply with the predetermined correction plan.

Rings 20 and 30 of external fixation system 10 may include a pluralityof extension tabs 50. In the illustrated example, each ring 20 and 30includes six extension tabs 50 spaced circumferentially around theperimeter of the respective rings, although more or fewer may besuitable depending on the particular components of the fixation system.In addition to what is described directly below, extension tabs 50 mayhelp increase the cross-sectional area of rings 20, 30 and thus providefor increased stiffness of the rings.

With this configuration, each ring 20, 30 includes a first innercircumferential row of holes 60 and a second outer circumferential rowof holes 70. As illustrated, the second outer circumferential row ofholes 70 may be only positioned on the plurality of extension tabs 50 onthe rings 20 and 30. It should be understood that although the secondouter circumferential row of holes 70 is shown in FIG. 1 as beingpositioned solely on extension tabs 50, top ring 20 and/or bottom ring30 may contain two complete rows of holes, for example with a completelycircular (or nearly completely circular) geometry. The use of extensiontabs 50, compared to two full circumferential rows of holes, may helpreduce overall bulk of rings 20, 30 and also provide for intuitive strutplacement for surgical personnel. The completely circular version ofrings 20, 30 with two full (or nearly full) rows of circumferentialholes may be particularly suited for relatively small diameter rings,although indentations or other features may be introduced to provide anintuitive interface for strut placement by surgical personnel. Further,in the illustrated embodiment, the first and second circumferential rowsof holes 60 and 70 are positioned so that the first row of holes 60 doesnot align radially with the second row of holes 70. In other words, thefirst row of holes 60 has a staggered configuration with respect to thesecond row of holes 70. The additional hole options may also be utilizedfor connecting other components, such as fixation pins to couple therings 20, 30 to the respective bone fragments. Still further, thestaggered configuration of holes between the first and second rows 60,70 may also help prevent interference between components attached tonearby holes, for example such as a strut 100 a-f positioned in a firsthole and a fixation pin or other fixation member attached to an adjacentor nearby second hole. For example, a relatively thin wire extendingradially from one of the holes in the first circumferential row 60 maynot radially interfere with a hole positioned in the secondcircumferential row 70 because of the radial staggering. It should beunderstood that the size of the tabs 50 may increase or decreasedepending on the diameter of the rings 20 and 30, with greater diameterrings 20 and 30 having larger tabs 50 with more holes 70 compared tosmaller diameter rings. For example, the illustrated tabs 50 include sixholes 70, and a smaller ring may include smaller tabs with four holeseach, for example.

FIG. 2A illustrates a perspective view of one telescopic strut 100 fromthe external fixation system 10 of FIG. 1 . It should be understood thatthe components of struts 100 a-f may be identical to one another,although some struts 100 a-f may have different sizes than other struts100 a-f and may include different indicia, such as colors or markingsfor identification purposes, as described in greater detail below. Forpurposes of this disclosure, the term proximal refers to the top of thestrut 100 in the orientation of FIG. 2A, and the term distal refers tothe bottom of the strut 100 in the orientation of FIG. 2A. The proximalend portion of strut 100 may include a first joint 110, which is shownin this example as a universal joint. Joint 110 may include a proximalportion 111, which may include a first aperture 112 alignedsubstantially parallel with the longitudinal axis of strut 100 and asecond aperture 113 aligned substantially transverse or orthogonal tothe first aperture 112. The first aperture 112 may be configured toreceive a fastener that passes through a hole in proximal ring 20 tosecure the proximal portion 111 of joint 110 to proximal ring 20. Thefastener may be connected so that the proximal portion 111 does notrotate relative to proximal ring 20. The second aperture 113 may beconfigured to receive a portion of a tool to prevent proximal portion111 from rotating, for example while a fastener is being screwed into orotherwise inserted into first aperture 112. Joint 110 may also include adistal portion 115 with a first aperture 116 and a second aperture 117,the first and second apertures 116, 117 being aligned substantiallytransverse and/or orthogonal to one another and to the longitudinal axisof strut 100. First and second apertures 116, 117 may be used asattachment points for attaching additional components to strut 100 suchas modular attachment piece 180 shown in FIG. 3 and further described inU.S. Ser. No. 15/181,614 titled “Gear Mechanisms for Fixation FrameStruts,” the disclosure of which is incorporated by reference herein inits entirety.

Still referring to FIG. 2A, strut 100 may include additional componentsincluding an actuation mechanism 120, a quick-release mechanism 130, astrut identifier 140, a threaded rod 150 (not visible in FIG. 2A), atube 160, and a second joint 170. As noted above, the effective lengthof strut 100, which may be thought of as the distance between theproximal end and distal end of strut 100, may be adjusted by threadingthe threaded rod 150 of strut 100 into or out of tube 160 throughinteraction with quick-release mechanism 130.

FIG. 2B illustrates strut 100 with tube 160 omitted for clarify ofillustration. FIG. 2C illustrates strut 100 with tube 160, as well asquick-release mechanism 130, strut identified 140, and second joint 170omitted for clarity of illustration.

Actuation mechanism 120 is shown isolated in FIG. 2D. Actuationmechanism 120 may be generally a short, cylindrical component with aplurality of ridges or gear teeth 122 extending around the circumferenceof actuation mechanism 120. The actuation mechanism 120 may be rotatablycoupled to threaded rod 150 so that rotation of actuation mechanism 120causes a corresponding rotation of threaded rod 150. For example,actuation mechanism 120 may have a channel 124 extending therethrough,with an extension 126 in channel 124 that mates with a correspondingextension in threaded rod 150, so that rotation of actuation mechanism120 causes rotation of threaded rod 150. It should be understood thatthe threaded rod 150 may rotate with respect to the first joint 110, thefirst joint 110 and second joint 170 being rotatably fixed to rings 20and 30, respectively. The proximal surface of actuation mechanism mayinclude a plurality of divots of grooves 128 sized to accept a ballwhich is biased into the groove via a spring. The spring may have afirst end in contact with a distal surface of first joint 110, with adistal end pressing a ball into the proximal surface of actuationmechanism 120. With this configuration, an amount of force is requiredto rotate actuation mechanism 120 to overcome the force of the springpushing the ball into the divot 128. As rotation of actuation mechanism120 continues, the ball will eventually be positioned adjacent anadjacent groove 128. As rotation continues further, the spring willforce the ball into the next groove 128 when the ball is aligned withthe groove 128, causing a tactile and/or audible click. Each “click” maycorrespond to a particular axial change in length so that a user knows,for example, that four “clicks” correspond to 1 mm of length adjustment.Similar “clicking mechanisms” are described in greater detail in U.S.Pat. No. 8,834,467, the contents of which are hereby incorporated byreference herein.

Referring now to FIGS. 2A-B, quick-release mechanism 130 may generallytake the form of an outer housing that surrounds a portion of threadedrod 150. Quick-release mechanism 130 may have a disengaged state and anengaged state. In the disengaged state, threaded rod 150 may be capableof moving into or out of tube 160 without rotation of the threaded rod150, for quick adjustments of the length of strut 100, which may beuseful for example while initially assembling the fixation frame 10.Rotating the quick-release mechanism 130 may transition thequick-release mechanism 130 into the engaged state, in which threatedrod 150 may only move axially into or out of tube 160 via rotation ofthe threaded rod 150. The mechanism for keeping the quick-releasemechanism 130 in the engaged state may include a ball or other featurethat is forced between adjacent threads of threaded rod 150 so thataxial translation of the threaded rod 150 is only possible via rotation,so that rotation of threaded rod 150 axially moves the threaded rod 150into the tube 160, without requiring the tube 160 to have internalthreading. It should be understood that the quick-release mechanism 130is not a necessary component of strut 100, and may be omitted from strut100 if desired. If quick-release mechanism 130 is omitted, it may bepreferably to include internal threads on tube 160 to correspond toexternal threads on threaded rod 150. Further details of quick-releasemechanisms have been described elsewhere, including, for example, inU.S. Pat. No. 9,101,398, the contents of which are hereby incorporatedby reference herein.

A strut identifier 140 may be coupled to strut 100 at any desiredlocation, for example between the quick-release mechanism 130 and thetube 160. Strut identifier 140 may take the form of a clip or any othersuitable shape that can be quickly and securely clipped onto the strut100 and removed from strut 100. For example, in the illustratedembodiment, strut identifier 140 is a “C”-shaped clip that is flexibleenough to open for easy connection to strut 100, but rigid enough thatthe strut identifier 140 is not easily removed from strut 100 withoutintentional application of force. Strut identifier 140 may have a coloror other identifier such as a number, letter, or shape pattern. Eachstrut 100 a-f may have a strut identifier 140 that is structurallysimilar or identical, but that each has easily distinguishable indicia,such as different colors, different numbers, etc. Strut identifiers 140may be used so that each strut 100 a-f is easily distinguished from oneanother, and so that other matching indicia may be provided on othercomponents, described in greater detail below, that may be added ontostruts 100 a-f so that each additional component may be easily matchedwith the correct corresponding strut 100 a-f. Strut identifier 140 mayalso function to prevent unintentional disengagement of the quickrelease mechanism 130.

Referring again to FIG. 2A, tube 160 may be a generally hollowcylindrical tube configured to allow threaded rod 150 to move axiallyinto or out of tube 160 to decrease or increase the effective length ofstrut 100, respectively. As noted above, such axial movement may beproduced by rotation of threaded rod 150 when the quick releasemechanism 130 is in the engaged position, so that the threads of thethreaded rod 150 engage the ball or other mechanism within the quickrelease mechanism 130. If omitting the quick release mechanism 130, thetube 160 may include internal threads that mate directly with theexternal threads of the threaded rod 150. A slot 162 may extend alongpart of the length of the tube 160, the slot 162 opening the hollowinside of the tube 160 to the exterior of the tube at both inner andouter sides such that there are two slots 162 at least one of which willbe visible to the user depending on the orientation of tube 160 duringuse. The slot 162 may have a width slightly larger than the width ofbutton 152. Referring now to FIGS. 2B-C, the distal end of threaded rod150 may include a button 152 coupled to a collar 154, the collar 154surrounding the distal end of threaded rod 150. Collar 154 may bepositioned with a groove at the distal end of threaded rod 150 so thatcollar 154 may rotate freely around the axis of the strut 100 whilebeing axially fixed with respect to the threaded of 150. Referring againto FIG. 2A, as threaded rod 150 is threaded into or out of tube 160,button 152 travels up or down the slot 162 of the tube 160, which ispossible because button 152 and collar 154 are free to rotate withrespect to threaded rod 150. Tube 160 may include indicia, such as hashmarks and/or measurements, on or adjacent to slot 162. The position ofbutton 152 along slot 162 may correspond to the effective length of thestrut 100, so that a user can easily determine the effective length ofthe strut based on the indicia adjacent to the position of button 152 atany particular time.

Referring still to FIG. 2A, the distal end of tube 160 may include twoextensions that form a proximal portion 171 of second joint 170. Secondjoint 170 may include a distal portion 175 that, together with proximalportion 171 and an internal mechanism form a universal joint similar tofirst joint 110. Distal portion 175 may include a first aperture 176that is aligned substantially parallel with strut 100. Aperture 176 maybe adapted to receive a fastener therein to couple second joint 170 todistal ring 30. The fastener may be a screw or other type of fastener,and may be adapted to tightly couple the second joint 170 to the distalring 30 so that the second joint 170 does not rotate with respect todistal ring 30. With this configuration, the slot 162 of tube 160 may bepositioned outward (away from the center of proximal and distal rings20, 30) so that the position of button 152 with respect to indicia ontube 160 may be easily read at all times. The distal portion 175 ofsecond joint 170 may include a second aperture 177 aligned substantiallyorthogonal to first aperture 176 and adapted to receive a tool to keepsecond joint 170 from rotating, for example while a fastener is screwedinto first aperture 176. This may help ensure, for example, the slot 162of tube 160 is facing away from the center of the rings 20, 30 as thestrut 100 is tightened to the rings 20, 30. It should also be understoodthat in some prior art devices, rotational freedom of the strut wasprovided by loosely coupling the joint(s) to the ring(s) so that thejoints themselves could swivel. In the present disclosure, therotational degree of freedom is provided by the ability of threaded rod150 to rotate, while the tight attachment of the first joint 110 andsecond joint 170 to the first ring 20 and second ring 30 provides for amore stable connection.

It should be understood that strut 100 as described above may bedesigned for manual actuation, for example by a user gripping theactuation mechanism 120 with his hand and manually rotating theactuation mechanism 120. However, it should be understood that a toolmay be used, either directly on actuation mechanism 120 or withintervening components, to adjust the length of strut 100. For example,FIG. 3 illustrates the external fixation system 10 of FIG. 1 withcompletely identical components, with the exception that each strut 100a-f includes a modular attachment piece 180 coupled to a correspondingstrut 100 a-f. As is described in U.S. Ser. No. 15/181,614 incorporatedby reference herein, modular attachment piece 180 provides a variety ofbenefits, including a simple way to allow a user to adjust struts 100a-f with a tool rather than through manual adjustment.

FIG. 4 is a perspective view of an external fixation system 10′according to another embodiment of the disclosure showing strutattachment members 310, 370 of the present invention each coupling firstand second struts 200 a, 200 b to respective first and second rings 20,30. FIG. 5A is a perspective view of first strut 200 a with strutattachment members 310, 370 coupled to the strut in a firstconfiguration while FIG. 5B is a perspective view of second strut 200 bwith strut attachment members 310, 370 coupled to the strut in a secondconfiguration. In reference to first and second struts 200 a, 200 b,each may include additional components including an actuation mechanism220, a quick-release mechanism 230, a strut identifier 240, a threadedrod 250 (not visible in FIGS. 5A, 5B), a tube 260 and a slot 262extending along the length of the tube 260. As noted above, theeffective length of struts 200 a, 200 b, which may be thought of as thedistance between the proximal end and distal end of strut 200 a, 200 b,may be adjusted by threading the threaded rod 250 of each strut 200 a,200 b into or out of tube 260 through interaction with quick-releasemechanism 230.

In reference to FIGS. 5A and 5B, the proximal end portion of each strut200 a, 200 b include a first strut attachment member 310 instead offirst joint 110 shown, for example, in FIG. 2 a . Each strut 200 a, 200b also include a translatable second strut attachment member 370 insteadof fixed location second joint 170 as also shown, for example, in FIG. 2a.

Strut attachment member 310 is pivotably coupled at a first end thereofto a first ring member 20, 30 and at a second end thereof to a first endof adjustable length strut 200 a, 200 b. Strut attachment member 370 ispivotably coupled at a first end thereof to a second ring member 20, 30and at a second end thereof to a length of the adjustable length strut200 a, 200 b. The struts of the present invention has at least two modesof operation, such as “Long mode” in reference to strut 200 a and “ShortMode” in reference to strut 200 b.

When the surgical indication require a very tight right to ringdistance, strut attachment member 310 is fixed to a proximal ring, forexample, while strut attachment member 370 is attached to a middleportion of the strut, followed by attaching that level to the distalring, for example. At this point, the struts will be either in theminimum distance between the joints or somewhere between the minimum andthe maximum distance of the joints. During correction when the strut isextended to the maximum length, which is represented by the indicatorpins touching the top of the slot of the tube, the strut change outdevice is applied. The strut change out device holds the two rings tightwith respect to each other. At this point bottom joint that is attachedto the middle of the strut is unlocked followed by unlocking the quickrelease. The whole tube is moved up and spun 180° so that the slot onthe opposite direction that used to face inwards now faces outwards. Thebottom joint is now locked at the bottom end of the strut, followed bylocking the quick release. This will result in the “Long Mode” of strutoperation. This will allow the same strut to get another full length oftelescoping to allow maximum distraction just with one strut.

FIG. 6A is a perspective view of strut attachment member 370 of thepresent invention that is configured to be coupled about the tube orbody 260 of struts 200 a, 200 b. Strut attachment member 370 includes aring connector portion 372, an intermediate portion 380 and a couplingportion 390. Strut attachment member 370 allows for two degrees offreedom between the strut and a respective ring that the strut iscoupled to. The two degrees of freedom is obtained by utilizing onepivot joint and one hinge joint. FIG. 6B shows ring intermediate portion380 and coupling portion 390 of strut attachment member 370 without ringconnected portion 372. As shown in FIG. 6C, ring connector portion 372includes a corner ledge portion 373 for receipt of a correspondingcorner of rings 20, 30 to position ring connector portion 372 and toprevent rotation thereof prior to fixing ring connector portion 372 torings 20, 30. A fastener (not shown) is received within aperture 374 anda hole of rings 20, 30 in order to secure ring connector portion 372 torings 20, 30. Ring connector portion 372 includes first and secondlateral bores 379 for receipt of pins (not shown) in order to securepost 382 of intermediate portion 380 within transverse aperture 375 ofring connector portion 372 defining a pivot joint.

As shown in FIG. 6B, post 382 includes a circular recess 383 therein,the pins being received in a portion of the recess after post 382 isfully received within transverse aperture 375 of ring connector portion372 in order to secure post 382 of intermediate portion 380 withintransverse aperture 375 while allowing intermediate portion 370 to pivotor rotate about a longitudinal axis L1 with respect to ring connectorportion 372. Ring connector portion 372 further includes an innersurface 376 and an outer surface 377. The inner surface 376 isconfigured to lie adjacent a planar top or bottom surface of rings 20,30 when ring connector portion 372 is coupled to rings 20, 30.Intermediate portion 380 further includes a u-shaped portion 384extending from secure post 382. The u-shaped portion 384 includes firstand second legs 385, 386 having apertures 388. A pivot pin 389 isreceived within apertures 388 of first and second legs as well as anaperture (not shown) in an extension 392 of coupling portion 390. Pivotpin 389 forms a hinge joint between intermediate portion 380 andcoupling portion 390 and allows intermediate portion 380 to pivot withrespect to coupling portion 390 about a longitudinal axis L2perpendicular to L1. Coupling portion 390 further includes a bore 394for receipt of tube 260 and a movable pin 396 received within anaperture 397 of coupling portion 390. Movable pin 396 is moved about anaxis L3 in order to position coupling portion 390 within a correspondingfeature 264 a, 264 b of tube 260 in order to position strut attachment370 in either a first position as shown for example in FIG. 5A or asecond configuration as shown for example in FIG. 5B.

FIG. 7 is a perspective view of strut attachment member 310 of thepresent invention that is configured to be coupled at an end of a strut.Strut attachment member 310 includes a ring connector portion 312(similar to ring connector portion 372), an intermediate portion 320(similar to ring connector portion 380) and a coupling portion 330.Coupling portion 300 includes a longitudinal bore 332 for receipt of apost 222 in order to couple coupling portion 300 to an end of the strut.Coupling portion 300 further includes a first aperture 316 and a secondaperture 317, the first and second apertures 316, 317 being alignedsubstantially transverse and/or orthogonal to one another and to thelongitudinal axis of struts 200 a, 200 b. First and second apertures316, 317 may be used as attachment points for attaching additionalcomponents to strut 200 a, 200 b such as modular attachment piece 180.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. For example, features described in relation to oneparticular embodiment may be combined with features of other embodimentsdescribed herein. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

1. An external fixation system comprising: a first ring member definingan outer proximal surface and an opposite inner distal surface; a secondring member defining an outer distal surface and an opposite innerproximal surface, the inner proximal surface of the second ring memberfacing the inner distal surface of the first ring member; a first strutattachment member having a first portion coupled to the outer proximalsurface of the first ring member and a second portion coupled to a firstend of an adjustable length strut, and a third portion pivotably coupledto the first and second portions, the third portion having a pivotportion pivotably coupling the first and third portions, the firstportion including a bore configured to receive a fastener, the boreextending along an axis extending from the outer proximal surface to theinner distal surface of the first ring member, and a second strutattachment member having a first portion coupled to the outer distalsurface second ring member and a second portion coupled to a length ofthe adjustable length strut, and a third portion pivotably coupled tothe first and second portions.
 2. The external fixation system of claim1, wherein the first strut attachment member includes a pin, the pinpivotably coupling the second and third portions of the first strutattachment member.
 3. The external fixation system of claim 1, whereinthe fastener is configured to secure the first portion of the firststrut attachment member to at least one of a plurality of holes in thefirst ring member.
 4. The external fixation system of claim 1, whereinthe first portion of the second strut attachment member is coupled tothe outer distal surface of the second ring member.
 5. The externalfixation system of claim 1, wherein the adjustable length strutcomprises: a rod member extending between the first end and a second endof the adjustable length strut, the rod member including externalthreads; a tube member extending between the first and second ends ofthe adjustable length strut, the tube member including a hollow portionadapted to receive the rod member and an engagement feature adapted toengage the external threads of the rod member; and an actuationmechanism rotatably fixed to the rod member, the actuation mechanismincluding a plurality of gear teeth extending radially outward of alongitudinal axis of the rod member.
 6. The external fixation system ofclaim 5, wherein the adjustable length strut further comprises aprotrusion member coupled to an end portion of the rod member, theprotrusion member extending substantially orthogonal to the longitudinalaxis of the rod member, the protrusion member includes a collar portionsubstantially surrounding the end portion of the rod member, wherein thecollar portion is freely rotatable with respect to the end portion ofthe rod member.
 7. The external fixation system of claim 6, wherein thetube member includes an elongate slot extending through inner and outersurfaces of the tube member, a portion of the protrusion member extendsthrough a portion of the elongate slot, and wherein the tube memberincludes visual indicia on the outer surface thereof adjacent the slot.8. An external fixation system comprising: a first ring member definingan outer proximal surface and an opposite inner distal surface; a secondring member defining an outer distal surface and an opposite innerproximal surface, the inner proximal surface of the second ring memberfacing the inner distal surface of the first ring member; a first strutattachment member having a first portion coupled to the first ringmember and a second portion coupled proximate to a first end of anadjustable length strut, and a third portion pivotably coupled to thefirst and second portions, the third portion having a pivot portionpivotably coupling the first and third portions; and a second strutattachment member having a first portion coupled to the outer distalsurface of the second ring member and a second portion coupled to anouter surface of the adjustable length strut between the first end asecond end of the adjustable length strut, and a third portion pivotablycoupled to the first and second portions.
 9. The external fixationsystem of claim 8, wherein the first strut attachment member includes apin, the pin pivotably coupling the second and third portions of thefirst strut attachment member.
 10. The external fixation system of claim8, wherein the first portion of the second strut attachment member has abore adapted to receive a fastener for securing the first portion of thesecond strut attachment member to at least one of a plurality of holesin the second ring member.
 11. The external fixation system of claim 8,wherein the first portion of the first strut attachment member iscoupled to the outer proximal surface of the first ring member.
 12. Theexternal fixation system of claim 8, wherein the adjustable length strutcomprises: a rod member extending between the first and second ends ofthe adjustable length strut, the rod member including external threads;a tube member extending between the first and second ends of theadjustable length strut, the tube member including a hollow portionadapted to receive the rod member and an engagement feature adapted toengage the external threads of the rod member; and an actuationmechanism rotatably fixed to the rod member, the actuation mechanismincluding a plurality of gear teeth extending radially outward of alongitudinal axis of the rod member.
 13. The external fixation system ofclaim 12, wherein the adjustable length strut further comprises aprotrusion member coupled to an end portion of the rod member, theprotrusion member extending substantially orthogonal to the longitudinalaxis of the rod member, the protrusion member includes a collar portionsubstantially surrounding the end portion of the rod member, wherein thecollar portion is freely rotatable with respect to the end portion ofthe rod member.
 14. The external fixation system of claim 13, whereinthe tube member includes an elongate slot extending through inner andouter surfaces of the tube member, a portion of the protrusion memberextends through a portion of the elongate slot, and wherein the tubemember includes visual indicia on the outer surface thereof adjacent theslot.
 15. An external fixation system comprising: a first ring memberdefining an outer proximal surface and an opposite inner distal surface;a second ring member defining an outer distal surface and an oppositeinner proximal surface, the inner proximal surface of the second ringmember facing the inner distal surface of the first ring member; a firststrut attachment member having a first portion coupled to the outerproximal surface of the first ring member and a second portion coupledto a first end of an adjustable length strut, and a third portionpivotably coupled to the first and second portions, the third portionhaving a pivot portion pivotably coupling the first and third portions;and a second strut attachment member having a first portion coupled tothe outer distal surface of the second ring member and a second portioncoupled to one of a plurality of positions about the length of theadjustable length strut between the first end and a second end of theadjustable length strut, and a third portion pivotably coupled to thefirst and second portions.
 16. The external fixation system of claim 15,wherein the first strut attachment member includes a pin, the pinpivotably coupling the second and third portions of the first strutattachment member.
 17. The external fixation system of claim 15, whereinthe first portion of the first strut attachment member has a boreadapted to receive a fastener for securing the first portion of thefirst strut attachment member to at least one of a plurality of holes inthe first ring member.
 18. The external fixation system of claim 15,wherein the first portion of the first strut attachment member islocated proximally to a top surface of the first ring when the firststrut attachment member is coupled to the first ring member.
 19. Theexternal fixation system of claim 15, wherein the adjustable lengthstrut comprises: a rod member extending between the first and secondends of the adjustable length strut, the rod member including externalthreads; a tube member extending between the first and second ends ofthe adjustable length strut, the tube member including a hollow portionadapted to receive the rod member and an engagement feature adapted toengage the external threads of the rod member; and an actuationmechanism rotatably fixed to the rod member, the actuation mechanismincluding a plurality of gear teeth extending radially outward of alongitudinal axis of the rod member.
 20. The external fixation system ofclaim 19, wherein the adjustable length strut further comprises aprotrusion member coupled to an end portion of the rod member, theprotrusion member extending substantially orthogonal to the longitudinalaxis of the rod member, the protrusion member includes a collar portionsubstantially surrounding the end portion of the rod member, wherein thecollar portion is freely rotatable with respect to the end portion ofthe rod member.